To evaluate the seismic hazard for the Corps dams in the Portland District, operating basis earthquakes (OBE) and maximum credible earthquakes (MCE) were established for seismic zones from Bonneville Dam in the north to Applegate Dam in southern Oregon. Capable faults are included in the MCE map. The accelerations produced by these earthquakes were determined by using a Greensfelder's graph of acceleration versus distance for various magnitudes. The changes in the maps produced by using other acceleration functions would not be significant. The OBE map shows areas within Oregon with greater than . 2g. The higher values are found to the southwest (San Andreas system), and to the north toward Olympia, Washington. This study indicates that there are significant seismic accelerations possible and that seismic considerations are needed for critical structures in Oregon.